1. Field of the Invention
The present invention relates to a motor control device and a motor system equipped with the motor control device.
2. Description of Related Art
The background art related to a system equipped with motors used as drive sources is disclosed, for instance in Japanese Laid Open Patent Publications H9-47055 and 2006-42416.
Japanese Laid Open Patent Publication H9-47055 discloses a technology whereby the power supply from an inverter to a permanent magnet synchronous motor operating under field-weakening control is stopped by shorting input terminals of the permanent magnet synchronous motor if an anomaly occurs as a main switch located between the main battery and the inverter enters an open state, so as to ensure that a voltage at a level equal to or higher than the required level is not applied to a smoothing capacitor connected to the DC input side of the inverter switching unit. Input terminals of the permanent magnet synchronous motor are shorted by turning on all the upper arms or all the lower arms in the inverter switching unit.
Japanese Laid Open Patent Publication 2006-42416 discloses a technology whereby a system main relay, disposed between a battery and an inverter to electrically connect them or electrically disconnect them from each other, is turned off when the voltage due to a back electromotive force generated at a motor becomes higher than the voltage on the battery side.